JP6416922B2 - Improved directivity adjustable sound system - Google Patents

Description

  The present invention relates to control of directivity of an electronic sound source. Whether used in professional, industrial or home acoustic systems.

  Electronic sound sources are commonly referred to as “acoustic speakers”, “loud speaker systems”, “source lines”, or “sound speakers or systems”.

  Among the essential features that make sound sources appropriate, directivity, more specifically, the method of controlling directivity over a limited portion of the speech spectrum, plays an important role in professional applications. In general, in the angle region that designates an angle corresponding to the angle region, the sound pressure level (SPL), that is, SPL is constant in the frequency range specified by the manufacturer. Therefore, for example, such a sound source is said to exhibit 90 ° horizontal directivity controlled from 1 kHz to 10 kHz. According to international conventions, the term “controlled” includes the meaning that SPL is constant within +/− 3 dB in the 90 ° region between 1 kHz and 10 kHz. In contrast, the attenuation of SPL outside this angular region should be as high as possible, typically higher than 6 dB.

  In professional acoustic systems, the directivity of the sound source distinguishes between two planes, a horizontal plane and a vertical plane. In the two planes, this characteristic generally exhibits different values. The technology for controlling the directivity of the sound source goes back to the origin of the loudspeaker.

  Today, there are two independent methods that can control the directivity of the sound source. The first is conventional mechanical, which is very much based on the use of sound horns and / or an array of several transducers. “Sound source” products belonging to this class have a single directivity that is set only once depending on the material configuration of the components of the acoustic speaker, for a given horizontal or vertical surface, regardless of whether they are in the professional field. Show. Thus, the choice of transducers, their connection frequency, the type of horn or waveguide guide attached to the front of the compression chamber drive or electrodynamic speaker opening, therefore, more or less extended spectral bandwidth. Determine the directivity characteristics of the sound source.

  Recall that only frequencies in the mid and high frequencies are controlled, as it is known that all frequencies with wavelengths far exceeding the physical dimensions of the sound source object cannot be controlled by the inevitable laws of physics. It is. Therefore, if the acoustic speaker is a cube having a side of 30 cm, a frequency lower than 100 Hz, that is, a wavelength larger than 3.4 m cannot be controlled. At intermediate frequencies, i.e. intermediate frequencies that correspond to mid-range loudspeakers whose frequency is typically between about 200 kHz and about 1 kHz, an ad hoc arrangement of the transducer is used to reduce the interference between several loudspeakers. It is possible to obtain good control by acting. At high frequencies, i.e. high frequencies for high-frequency loudspeakers whose frequency is typically between about 1 kHz and about 10 kHz, to obtain the desired orientation by the shape of the guide and / or horn, It is necessary to attach a waveguide guide and / or horn in front of an opening or mouthpiece of a commonly called high-frequency loudspeaker or compression chamber drive.

  The advantage of the mechanical approach is its simple design and reasonable cost, which provides interesting results at medium / high frequencies. A drawback due to mechanical invariance is that the same product cannot provide the user with several options for directivity.

  This shortcoming has led to the introduction of a variably arranged horn or waveguide guide that is adjusted by the user according to the user's choice by inserting a directional flap at the output end of the waveguide guide. It also has a directional variable element built into the midrange converter and has the name MINI COM.PASS (registered trademark) of the outline belonging to the first class of mechanically operating sound sources The device is known. Unfortunately, since such a setting only affects some physical parameters of the mid / high tone set, the level of performance throughout the entire desired frequency range is limited.

  A second method of controlling directivity has emerged during the last decade, which is based on electronic means provided by DSP type components (DSP stands for digital signal processor). Many identical transducers are related according to a predefined physical arrangement. The transducer operates over the normal frequency range selected by the manufacturer. Thanks to the DSP component, amplitude and phase parameters, i.e. filtering, gain, phase shift, delay time parameters, are applied to at least one of the transducers to modify the directivity of the loudspeaker assembly, which is considered a composite sound source. Allows you to control. The advantage of this approach is the ability to provide different directivity for the same physical configuration. This indicates that a significant number of transducers are always required to obtain high quality control. The disadvantage is the high cost of implementing converter-amplified DSP components in general, and typically as soon as the wavelength is smaller than the size of each converter at frequencies above 4 kHz. However, it becomes nearly impossible to deal with the problem of very high frequency control.

  Thus, the device described in EP 1 635 606 belongs to a first class of mechanically operated sound sources having adjusting flaps that act mechanically and acoustically on a mid / high range transducer. The method uses different DSP parameters for different flap settings, for the sole purpose of linearizing the frequency response. There is no frequency range common to mid / high range converters. The connection frequency between the mid-range and high-range transducers is fixed and is therefore independent of the flap orientation.

  The object of the present invention is to overcome the disadvantages of the known loudspeaker systems by providing a system that exhibits particularly effective directivity with a sufficiently simple adjustment.

  This object is achieved according to the invention for an acoustic system. The acoustic system emits a high range transducer to produce at least one high range transducer, at least one mid range transducer, and a high range transducer emission directivity corresponding to the selected angular range. A variable direction flap (6) acting on the sound, the midrange converter and the highrange converter are set to emit in a common frequency range, and the signal to the highrange converter and the midrange converter At least one digital signal processor-type control module acting on the signal to and applying at least one amplitude parameter on the high and / or mid range converter in a common frequency range, Applying at least one phase parameter on the detector (1) and / or the midrange converter, corresponding to the same selected angular region as the directivity generated by the variable direction flap And generating a sound emission directivity of the pair constituted by the range transducer and midrange transducer.

  Advantageously, the directional flaps and the DSP-type control module are each configured to generate a sound wave presence in response to a substantially constant sound pressure level within a selected angular region. The flap and DSP type control module is configured to attenuate the sound wave at any angle outside the selected angular region with an attenuation higher than 6 dB associated with the highest sound level within the selected angular region.

  Advantageously, the acoustic system is configured such that the common frequency range is variable based on the orientation of the directional flap.

  Advantageously, the acoustic system comprises at least two midrange transducers and at least one treble transducer, the midrange transducers being arranged on both sides of the treble transducer.

  Advantageously, the acoustic system includes a case that at least partially surrounds one of the flaps, at least one of the flaps being directed against the surface and the high-frequency conversion opposite the sound stream emitted by the high-frequency converter. The case has a surface directed away from the sound stream emitted by the instrument, the case in front of the surface of the flap (6) directed away from the sound stream emitted by the high range transducer Obstacles are formed to protect this surface from impact created by the object.

  Advantageously, the at least one mid-range transducer has a substantially conical movable diaphragm, and the case of the at least one flap is shaped to fit a generally conical shaped portion of the diaphragm.

  Advantageously, the acoustic system constitutes a portable acoustic system.

  Advantageously, the acoustic system comprises at least two bass transducers, the at least two bass transducers being arranged on both sides of an assembly constituted by at least one treble transducer and at least two midrange transducers. The

  Advantageously, the acoustic system comprises at least one waveguide guide that carries the sound waves emitted by the high range transducer.

  Advantageously, the acoustic system has a slot through which the sound waves generated by the high range transducer are emitted and at least two midrange transducers are arranged on either side of the slot.

  Other features, objects and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.

1 is a cross-sectional view of a loudspeaker system according to an embodiment of the present invention. It is sectional drawing of the direction variable flap part of this same loudspeaker system.

  The loudspeaker system shown in FIG. 1 includes a K-shaped configuration of a mid-range and high-range converter. When viewed from the front, the loudspeaker system is symmetric with respect to a vertical plane across the system at its center. Starting from the center of the front, there is a compression chamber drive 1 that is linearly incorporated. The compression chamber drive 1 is coupled to an overlaid waveguide guide 2 that presents an output end in the form of a vertical longitudinal slot 3 on the front surface. On both sides of the slot 3, a midrange converter 4 is incorporated on the front surface at a position closest to the slot 3. On both sides of these mid-range converters 4 are incorporated low-range converters 5 arranged close to the mid-range section.

  The high range converter 1 emits a high range frequency constituted by a frequency included between about 1 kHz and about 10 kHz. The midrange converter emits midrange frequencies composed of frequencies comprised between 200 Hz and about 1 kHz. The bass converter emits bass frequencies composed of frequencies below about 200 Hz.

  A wall 6 that partially hides the midrange converter 4 is added to both sides of the slot 3, and the direction of the wall is a high level emitted by the treble range converter 1 on an angle region according to the directivity of the high range. Enables frequency direction.

  Here, these walls 6 form variable direction flaps. Therefore, the mechanical setting of these direction variable flaps 6 is performed at the output end of the waveguide guide 2, and the waveguide guide is sequentially arranged in the opening of the high frequency converter 1 configured by the compression chamber driving unit. Connected. The assembly is placed between two or more mid-range transducers 4 that are mounted radially on the fixed surface so that the completed device is symmetric with respect to the vertical plane at the front. Here, the flap 6 located at the output end of the waveguide guide 2 is movable, and several directions can be selected in advance.

  Here, the flap 6 is trapped in two respective cases 7. Each case 7 extends around a space delimited by the lower surface of the flap 6 in a direction away from the high-frequency sound stream. Therefore, the case 7 protects the flap 6 so that an external object cannot contact the flap from below. Each case 7 houses and protects a pre-selected rotation and orientation system of the corresponding flap 6. In the present embodiment, each case 7 has a portion that overlaps with each mid-range converter. In this overlapping portion, each case 7 enters a conical space defined by the movable diaphragm of the mid-range converter 4 and conforms to the shape of the diaphragm. Therefore, this overlapping portion functions as a mid-range compression chamber.

  Here, the flaps 6 can be individually directed, and for the present system whether right or left depends on which flap is located at the most elevated position. An asymmetric setting of the direction of the sound stream can be adopted.

  The rotation of the flap 6 can change the directivity of the high range over the operating range of the high range transducer, typically at a frequency in the range of 800 Hz or more, however, the size of the flap 6 can be open or closed. The condition is that the mode is large enough to ensure effective control. In fact, due to the physical dimensions that are too small at the output end of the flap, attention should be paid to the loss of directivity control such that the flap is tightened over a narrow angular region.

  In order to eliminate this effect, one setting that innovatively activates these converters using a DSP was introduced in the midrange converter of the present system to reduce the loss of midrange control in its lower part. Compensate acoustically.

  In this apparatus, the mid-range converter 4 and the high-range converter 1 operate in a common frequency range, and the DSP component sets the amplitude and phase parameters of the high-range transducer 1 and the mid-range converter 4 over the common frequency range. The directivity achieved by the parameters is set to be the same as the directivity generated by setting the flap 6 in the high sound range. For this purpose, at least three source points consisting of a central high-frequency converter 1 and two identical mid-range converters 4 located on both sides thereof are electronically coupled by the DSP itself. Is a known method, and the resulting acoustic sum is converted to the desired directivity.

  In other words, the process consists of adjusting the filtering, gain, phase and delay parameters, so that the delay is equivalent to a frequency dependent phase shift and the filtering is equivalent to a frequency dependent amplitude. This is the same as the present embodiment. This technique is generalized, for example, with a few additional source points located on both sides of the device described above, and with lower frequency control to increase step by step, with other sections and To relate. Therefore, a loudspeaker system is realized in which the directivity is variable not only due to fluctuations in the direction of the directional flap but also due to cooperative fluctuations in processing applied by the DSP component.

  Here, the high frequency range converter 1 is supplied not only with digital signal processing but also with amplification by a DSP component included in the mounted control module. The high pass filter for the transition between the mid-range frequency and the high-range frequency is set to the value Fc. In the present embodiment, the gain and delay of the high frequency range are adjusted in relation to the mid range so that the acoustic sum is most advantageous in the maximum angular range 110 °. The gain attenuation is related to the nominal gain in the sub-Frc frequency range that varies between Fc and Fc × 2.5 depending on the orientation of the flap 6, over a frequency range of [Fc, Frc], This is realized by a value lower than 6 dB and changing according to the direction of the flap. The additional delay is applied to the high frequency range portion that changes according to the direction of the flap. The midrange converter 4 is also provided by a control module that creates digital signal processing and amplification, where the number of these modules is one for each type of converter, It can be replaced with a plurality of control modules respectively corresponding to the converters. Here, the control module is arranged outside the loudspeaker system shown in the drawing, but as a modification, it may be integrated into such a loudspeaker system.

  When the mid-range converters are related in parallel, the low-pass filter for the transition between the mid-range and high-range frequencies is set to Fc, and the frequencies of the mid-range converter 4 and the high-range converter 1 are set. Is set to a value of Frc that varies between Fc and Fc × 2.5 in accordance with the direction of the flap 6. Here, in relation to the nominal gain over the frequency range below Frc, the attenuation of the gain over the frequency range of [Fc, Frc] is performed 4 with an attenuation value higher than 6 dB.

  The present loudspeaker system is constituted by a system that can be carried by one or two persons using handle means arranged at the end of the system.

  Therefore, in this embodiment, the frequencies and attenuations given in the table below are realized and assigned corresponding to the desired directivity, and these frequencies and attenuations can be changed depending on the physical configuration of the transducer. Yes, the value here is given for an Fc value equal to 1 kHz.

  The described device combines the mechanical setting of the sound source by use of the variable direction flap 6 acting on the high frequency range part and the setting of the converters of the low range 5, mid range 4 and high range 6 by the DSP component, Here, the common frequency range is changed depending on the direction of the flap 6 in the high sound range, and a frequency range common to at least two converter types is realized. The mechanical and electronic parameters are adjusted to extend the directivity control obtained in the high range relative to the mid range frequency reproduced by the mid range converter 4. Thus, the associated amplitude and phase parameters of the transducer are modified by the DSP component to obtain a match between high and mid-range directivities. Accordingly, by appropriate control from 300 Hz to a frequency exceeding 10 kHz, it is possible to adjust the directivity of the sound source including the device over an angular range in the range between 60 ° and 120 °.

Claims (9)

An acoustic system,
At least one treble converter (1);
At least one midrange converter (4);
A variable direction flap (6) acting on the sound output of the high sound range converter (1) so as to generate the sound output directivity of the high sound range converter (1) corresponding to the selected angle region. ,
The mid-range converter (4) and the high-range converter (1) are set to emit in a common frequency range, and the signal to the high-range converter (1) and the mid-range converter (4) At least one digital signal processor-type control module acting on the signal to the high-frequency converter (1) and / or the mid-range converter (4) in the common frequency range. Applying two amplitude parameters, applying at least one phase parameter on the high range transducer (1) and / or the mid range transducer (4), the directivity generated by the variable direction flap (6) Generating a pair of sound output directivities constituted by the high-range transducer and the mid-range transducer corresponding to the selected angular region that is the same as the frequency, and the common frequency range is the direction OK Sound system, characterized in that, being configured to be variable based on the orientation of the flap (6).   The variable direction flap and the DSP-type control module are each configured to generate the presence of a sound wave according to a substantially constant sound pressure level within the selected angular region, and the variable direction The flap (6) and the DSP-type control module transmit the sound wave at any angle outside the selected angular range according to an attenuation higher than 6 dB, which relates to the highest sound level within the selected angular range. The acoustic system of claim 1, wherein the acoustic system is configured to attenuate. It comprises at least two midrange converters (4) and at least one treble converter (1), and the midrange converter (4) is arranged on both sides of the high range converter (1). The sound system according to claim 1 or 2 . A case (7) that at least partially surrounds one of the flaps (6), wherein at least one of the flaps is directed against the surface of the sound stream emitted by the high range transducer (1); A surface oriented in a direction away from the sound stream emitted by the high sound range transducer (1), wherein the case (7) is away from the sound stream emitted from the high sound range transducer (1) in front of the surface of the flap (6) directed to, either to protect the surface from the impact produced by the outside of the object from claim 1 and forming an obstacle 3 1 The acoustic system according to item. The at least one midrange transducer (4) has a substantially conical movable diaphragm, and the case (7) of the at least one flap (6) fits into the generally conical portion of the diaphragm. The acoustic system according to claim 4 , wherein the acoustic system is shaped as follows. The acoustic system according to any one of claims 1 to 5 , wherein the acoustic system constitutes a portable loudspeaker system. Comprising at least two bass converters (5),
Said at least two bass transducers (5) are arranged on opposite sides of an assembly constituted by said at least one treble transducer (1) and said at least two midrange transducers (4). The acoustic system according to claim 3 . Acoustic system according to any one of claims 1 7, characterized in that it comprises at least one waveguide guides convey sound waves emitted (2) by the high range transducer (1). It has a slot (3) through which sound waves generated by the high range converter (1) pass and are emitted, and the at least two middle range converters (4) are arranged on both sides of the slot (3). The acoustic system according to claim 3 .

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